Control system



R. E. DE CAMP.

CONTROL SYSTEM.

APPLICATION FILED AUG-26, 1918.

1,392,250. PatentedSpt. 27,1921.

2 SHEETSSHEET I.

/5- l4 I5 UUEJIUUUIT'UUU WITNESSES: lNVENTOR R. E. DE CAMP.

CONTROL SYSTEM.

APPLICATION FILED AUG.26, 1918.

PatentedSept. 27, 1921.

2 SHEETS-SHEET 2.

INVENTOR fia y A. fie flaw 0 BY TTOIIQNEY WITNESSES:

UNITED STATES,

PATENT OFFICE.

RAY n. on our, on winxxNsnuac, PENNSYLVANIA, AssIoNon 'ro wnsrrNcnousnnnncrmc a MANUFACTURING COMPANY, A conronnrxon or PENNSYLVANIA.

common srs'rnn.

' Specification of Letters Patent.

Patented Sept. 27, 1921.

Application filed Angst 26, 1918. Serial No. 251,429.

To all whom it may concern:

' Be it known that I, RAY E. DE CAMP, a citizen of the United States,anda resident of Wilkinsbur in the county of Allegheny and State ofennsylvania, have invented a new and useful Improvement in ControlSystems, of which the following is a specification.

My invention relates to control systems and particularly to systems suchas those forming the subject matter of a copending application, SerialNo. 236,937, of H. D. James, May 27, 1918, and assigned to theWestinghouse Electric & Manufacturing Co.

Figures 1 and 2 of the said application represent motor-control systemsin which the acceleration of the motor is effected through theshort-circuiting of. a resistor by means of a plurality of contactors,the actu-' ating coils of which are energized by the closing of relaymembers which, in turn,

Fig. 1 is a diagrammatic view of a system arranged according to myinvention, and Figs. 2, 3 and'4 are, respectively, a side and an endelevation and a plan view of a preferred relay mechanism employed inconnection with the system or Fig.1. This relay mechanism constitutesthe subject matter of my copending application, Serial No. 241,259,current-limit relay, filed June 21, 1918.

Referring to Fig. 1, a motor, the armature of which is shown at 1 andthe shunt fieldmagnet winding at 2, is connected between line conductors3v and 4, the motorcircuit being controlled by a line contactor 5, witha. regulating resistor 6 normally in series with the armature 1. A startpush-button switch controls the closing of the contactor 5 through anactuating coil 8. The start push-button switch may be shunted by meansof a switch 9 mechanically interlocked with the contactor 5. One or moretrated) control the shunting of successive portions 13, 14 and 15 of theregulating resistor 6 through the medium of actuating coils 19, 2O and21. A coil 22 is connected in parallel circuit with the resistor 6, anda second coli 23 1s connected, in circuit with an external resistor 24of high resistance,'across the line conductors 3 and 4. The energizingof the coil 22, as explained below, causes the successlve closing ofrelay members 25, 26 and 27, in accordance with the strength of thecurrent passing through the 'coil 22. The relay member 27 controls theclosing of the clrcuit of the coil 23. The coil 19 and therelay member25 are series-connected in a circuit extending from the line conductor3, through the coil 19, the relay 25 and the. start and stop push-buttonswitches, to the line conductor 4. The coil 20 and the relay member 26,as well as the coil 21 and the relay member 27, are in parallel relationto the coil 19 and the relay member 25. The pressing of the stoppush-button will stop the motor.

The preferred form of device for use in the system of Fi 1 isillustrated in Figs. 2, 3 and 4. Brie y, it comprises a coil, thecurrent flowing through which creates a magnetic field which causes anarmature to close, thereby releasing a plurality of armatures, eachbearing a relay contact. member. These latter armatures are springoperated to closed-circuit positions, but, owing to the magnetic fieldabove mentioned, the power of the springs is temporarily overcome untilthe magnetic flux, produced by the electric current, falls topredetermined values. The armatures are thus operated in succession,depending for their operation on the period of acceleration of themotor.

An insulating panel 29 carries two brackets 30 and 31 supporting thecoils 22 and 23 which, when energized by current flowing through them,create magnetic fields for atltracting an armature 32 and any desirednumber of additional armatures 33, 34 and 35. v A compression spring 36is adjustably ,m0unted upon a non-ma-gnetizable rod 37,

- other ends of the members 41.

piece for the armatures 33, 34 and 35. A bar 40 is rigidly connected tothe rod 37 and nor.-

mally engages the armatures 33, 34 and 35.

The spring 36 thus normally maintains the armatures 33, 34 and 35 inopen position, with the members 41, which are carried by thesearmatures, in contact with the pole piece 39. The members 41 arepreferably of non-magnetizable material to prevent freezing. Thearmature 32 is provided with brackets 42, which are pivotally mountedupon the bracket 30, and is normally retained in the broken-lineposition, (Fig. 2), by a weak spring 43. The bracket 30 supports anon-magnetizable, U-shaped member 44, between the arms of which arepivotally mounted the armatures 3.3, 34 and 35, which carry,respectively, the movable contact members 45, 46 and 47 of the relaymembers 25, 26 and 27 shown in Figs. 2, 3 and 4 as closed. Thestationary contact members 48, 49 and 50 of the relay members 25, 26 and27 are mounted upon the insulating panel 29. Springs 51 are attached tolongltudinally adjustable members 52 and to the The pole piece 39 isprovided with longitudinally adjustable members 53 to regulate alr gaps54 between these members and the corresponding armatures. By means ofthis adjustment, or by means of the members'52, the action of themagnetic flux produced by the coils 22 and 23 may be so regulated thatthe armatures 33, 34 and 35 will be operated in roper sequence. I

he operation is as follows: Upon the actuation of the start push-button,the coil 8 is energized by means of a circuit extending from the lineconductor 3, through the 0011.8 and the start and sto pushbuttons, tothe line conductor 4. he contactor 5 and the switch 9 are thereuponclosed, the latter creating a short-circuit for the start push-button,which may thereupon be released, and the former closing the motorcircuit. Current then flows from the line conductor 3 through thearmature 1, the resistor 6 and the contactor 5, to the line conductor 4.A circuit is also established through the coil 22, in parallel to theresistor 6. The energizing of the coil 22 creates a magnetic field whichattracts the armature 32 to the pole piece 38 (Fig. 2). The rod 37 (Fig.2) is thereupon pressed inwardly in opposition to the force of thespring 36, forcing the bar 40 away from the armatures 33, 34 and 35. Themotion of the armature 32 is from the b oken-line to the full-lineposition of Fig. 2 If the current is above a previously selected safevalue, the flux of the magnetic field will overcome the forces of thesprings 51, and the armatures will remain with the stops 41 inengagement with the pole piece 39. As the motor accelerates and thecurrent begins to I die down, the magnetic fiux set up by the coil 22becomes weakened, After a time, when the flux ha decreased to-apredetermined value, the spring 51, attached to one of the armatures,say the armature 33, will overcome the flux of this field, so that therelay member 25 will be closed. The time when this operation occursdepends upon the air gap 54 and the tension of the spring 51. The relaymembers 26 and 27, however, remain open.

A circuit now exists from the line conductor 3, through the coil 19, therelay member 25, the switch 9, and the stop push-button, to the lineconductor 4. The closing of this circuit energizes the coil 19 whichcauses the closing of the contactor 10 and this, in turn, creates ashunt circuit for the portion 13 of the resistor 6. The motor thenfurther accelerates to decrease the voltage across the-terminals of thecoil 22 and thus weaken the magnetic field in the neighborhood of thiscoil, which permits the closing of the relay member 26. A circuit isthen made from the line conductor 3, through the coil 20, the relaymember 26, the switch 9, and the stop. push-button, to theline conductor4. The coil 20, thus becoming energized, causes theclosing of thecontactor 11 and the consequent shunting of the resistor 14. Afterthemotor is further accelerated, the magnetic field surrounding the coil 22is again weakened and the relay member 27 is closed, creating a circuitfrom the line conductor 3, through the coil 21, the relay member 27 theswitch 9 and the stop push-button, to the line conductor 4, therebycausing the energization of the coil 21 and the closing of the contactor12. The resistor 6 is then entirely shunted from the armature circuit,and the armature 1 is connected directly across the line.

The shunting of the entire resistor 6 deenergizes the coil 22 and tendsto release the armature 32 (Fig. 2) and open the relay members 25, 26and 27. This i prevented in In system by the coil 23 the circuit of whicclosed by the relay member 27 extends from the line conductor 3, throughthe coil 23, the resistor 24, the relay member 27 the switch 9 and thestop pushbutton, to the line conductor 4.

To stop the motor, the stop push-button switch is depressed to open thecircuit of the coil 23. The spring 36 then actuates the armaturemembers33, 34 and 35 to their respective open positions. Since thearmature members correspond to the relay members 25, 26 and 27 of Fig.1, the relays open the circuits of the corresponding actuating coils ofthe accelerating switches, and the latter open to insert the resistor 6in circuit with the motor. The circuit of the actuating coil 8 of lineswitch 5- is opened, also, by the stop push-button switch.

I claim as my invention:

1. In a motor-control system, the combination with an electric circuitincluding a resistor, of a circuit comprising a switch forshort-circuiting said resistor, and means for maintaining said resistorshort-circuited, said means comprising a relay member for controllingsaid switch and a coil energized in accordance with the position of saidrelay member.

2. In a motor-control system, the combination with an electric circuitincluding a resistor, of a circuit comprising a circuitcontrollingdevice for effecting the shunting of said resistor, an actuating coilfor said device in parallel relation to said resistor, and meanscontrolled by the closing of said device for maintaining the latterclosed.

3. In a motor-control system, the combi-' nation with an electriccircuit including a resistor, of means comprising a relay member foreffecting the shunting of said resistor, an actuating coil for saidrelay member in parallel relation to said resistor, and a coil adaptedto be energized upon the closing of said relay member to maintain thelatter closed.

4. In a motor-control system, the combination with an electric circuitincluding a resistor, and means comprising a plurality of' relay membersfor successively effecting the shunting of portions of said resistor, ofmeans dependent upon the voltage across said resistor for keeping saidrelay members open, means for successively closing said relay memberswhen the said voltage falls below predetermined values, and a coilenergized upon the operation of the last of said relay members to closefor maintaining said relay members closed when said resistor has beencompletely shunted.

5. In a control system, the combination with an electric motor, aresistor in circuit therewith, and means comprising a plurality ofswitches for successively shunting portions of said resistor, of a coilin parallel relation to said resistor, means dependent upon the value ofthe current in said 0011 for successively effecting the closing of saidswitches, and a coil energized substantially simultaneously with theoperation of the last of said switches to close for insuring that saidswitches remain closed during the normal operation of said motor.

6. In a motor-control system, the combination with a motor armature anda resistor in circuit therewith, of means comprising a plurality ofswitches for shunting said resister, a plurality of relay members forcontrolling said switches, and a holding coil for said relay members,one of said relay members being adapted to close the circuit of saidholding coil.

7. In a motor-control system, the combination with a motor having anarmature and a resistor in series therewith, of means comprising aplurality of switches for shortcircuiting said resistor, an actuatingcoil for each of said switches, a relay member for closing the circuitof each of said coils, a coil in parallel with said resistor forcontrolling said relay members, and a coil controlled by the last ofsaid relay members to close for controlling said relay members.

8. In a motor-control system, the combination with an electric motorhaving an armature, and a resistor in series therewith, of'a pluralityof switches for controlling said resistor, a plurality of relay membersfor controlling said switches, and a coil for insuring that said relzymembers remain closed after being actuated to such positions, said coilbeing energized upon the closing of one of said relay members.

9. The combination with an electric motor having an armature, a resistorin circuit therewith and a source of current for said motor, of a switchfor short-circuiting said resistor, a coil in parallel relation to saidresistor for causing the actuation ofsaid switch, and a coil energizedby the voltage of said source for maintaining said switch in itsactuated position.

In testimony whereof I have hereunto subscribed my name this 22nd day ofAugust, 1918.

RAY E. DE CAMP.

